There are competing time lines as to whether Jim or Pam has worked at Dunder Mifflin longer. In The Secret (2006), Jim tells Pam that he had a crush on her when she first started. This is contradicted in this episode, when Jim says that on his first day he was walked to his desk by Pam, who warned him about his desk mate, Dwight.
When Michael is about to leave for the website launch party, he tells the office that they can take off early. Angela, however, says that there is an office party for the launch, which she says she has been planning for two weeks. Later in the day, when Andy comes by Angela's desk, she complains that she has a lot to do for a party she has been planning for three weeks.
When Angela comes into the conference room, she puts out two ribbons on the window blinds. As Andy brings in the ice sculpture, the ribbons are no longer there. They end up on the other side of the room.
Jim and Michael are supposed to be driving to New York City, but when they supposedly cross over the border leaving Pennsylvania, through the windows of the car you can see terrain which is clearly in California, not New Jersey (which they would be crossing through to get to NYC). There are mountains and desert like conditions rather than dense woodland and rolling hills.
When Meredith asks Jim to sign her cast, he actually signs "John Krasinski" (the actor's real name) instead of Jim Halpert (the character's name). A dead give away is that after he is done writing, he dots two i's in the last name.